A medical researcher is interested in whether patients' left arms or right arms are longer. If 9 patients participate in this study (so that 9 left arms and 9 right arms are measured), how many degrees of freedom
Should the researcher use in her t-test critical value?
A) 8
B) 9
C) 16
D) 17

Question

Quizplus · Accepted Answer

The degrees of freedom for a paired t-test, which is appropriate here since the same patients' left and right arms are being compared, is n - 1, where n is the number of pairs. In this case, n = 9, so the degrees of freedom is 9 - 1 = 8.

A Medical Researcher Is Interested in Whether Patients' Left Arms